The present invention relates to a new and distinctive hybrid perennial rye grass, designated 1917 and the parental lines 71548 and 71550. There are numerous steps in the development of any novel, desirable plant germplasm. Plant breeding begins with the analysis and definition of problems and weaknesses of the current germplasm, the establishment of program goals, and the definition of specific breeding objectives. The next step is selection of germplasm that possess the traits to meet the program goals. The goal is to combine in a single variety or hybrid an improved combination of desirable traits from the parental germplasm. These important traits may include higher yield, resistance to diseases and insects, tolerance to drought and heat, and better agronomic quality.
Choice of breeding or selection methods depends on the mode of plant reproduction, the heritability of the trait(s) being improved, and the type of cultivar used commercially (e.g., F.sub.1 hybrid cultivar, pureline cultivar, etc.). For highly heritable traits, a choice of superior individual plants evaluated at a single location will be effective, whereas for traits with low heritability, selection should be based on mean values obtained from replicated evaluations of families of related plants. Popular selection methods commonly include pedigree selection, modified pedigree selection, and mass selection.
The complexity of inheritance influences choice of the breeding method. Backcross breeding is used to transfer one or a few favorable genes for a highly heritable trait into a desirable cultivar. This approach has been used extensively for breeding disease-resistant cultivars. Various recurrent selection techniques are used to improve quantitatively inherited traits controlled by numerous genes. The use of recurrent selection in self-pollinating crops depends on the ease of pollination, the frequency of successful hybrids from each pollination, and the number of hybrid offspring from each successful cross.
These processes, which lead to the final step of marketing and distribution, usually take from eight to 20 years from the time the first cross is made. Therefore, development of new cultivars is a time-consuming process that requires precise forward planning, efficient use of resources, and a minimum of changes in direction.
The breeder initially selects and crosses two or more parental lines, followed by repeated selfing and selection, producing many new genetic combinations. The breeder can theoretically generate billions of different genetic combinations via crossing, selfing and mutations. The breeder has no direct control at the cellular level. Therefore, two breeders will never develop the same line, or even very similar lines, having the same rye grass traits.
Each year, the plant breeder selects the germplasm to advance to the next generation. This germplasm is grown under unique and different geographical, climatic and soil conditions, and further selections are then made, during and at the end of the growing season. The inbred lines which are developed are unpredictable. This unpredictability is because the breeder's selection occurs in unique environments, with no control at the DNA level (using conventional breeding procedures), and with millions of different possible genetic combinations being generated. A breeder of ordinary skill in the art cannot predict the final resulting lines he develops, except possibly in a very gross and general fashion. The same breeder cannot produce the same line twice by using the exact same original parents and the same selection techniques.
Today's standard procedure for grass breeding is to select a population of the best plants, plant and then re-select again. This breeding and testing process gains uniformity through family selfing and crossing and may provide a new grass which can be named and sold to the general public. Examples include Nebraska 28 Switchgrass and Pawnee Big Bluestem, all developed by Dr. Lawrence Newell, U.S.D.A., located at the University of Nebraska at Lincoln.
Perennial rye grass is a valuable field crop. Currently, the rancher-farmer who desires a growing grass from early spring until late fall must have separate pastures, one of which is called a cool season pasture which will provide grazing early in the spring and in the late fall. A warm season pasture is used for the mid-season, during the warmer portion of the growing season. This warm season grass does not grow in the spring until frost has stopped and then grows only until the frost returns again in the fall. It is costly for the rancher-farmer to provide additional acres so that he can have both the cool season and the warm season pastures available for grazing. A cool season pasture normally goes dormant with air temperatures above 90.degree. F. A cool season grass also produces seed at the end of the cool spring season which triggers the plant dormancy period with reduced plant growth. Most grass plants provide vigorous growth up to and until seed production is completed. It would be very desirable to have a perennial rye grass which would produce vegetation growth during the whole growing season and eliminate the need for the separate pastures required for both warm-season and cool-season grasses. It also is desirable to have a rye grass which is awnless or with a very short awn to allow easier seed handling and planting.